Sputtering target, A1 interconnection film, and electronic component

ABSTRACT

A sputtering target consists essentially of 0.1 to 50% by weight of at least one kind of element that forms an intermetallic compound with Al, and the balance of Al. The element that forms an intermetallic compound with Al is uniformly dispersed in the target texture, and in a mapping of EPMA analysis, a portion of which count number of detection sensitivity of the element is 22 or more is less than 60% by area ratio in a measurement area of 20x20 mum. According to such a sputtering target, even when a sputtering method such as long throw sputtering or reflow sputtering is applied, giant dusts or large concavities can be suppressed in occurrence.

TECHNICAL FIELD

The present invention relates to a sputtering target suitable forformation of wiring of low resistance, an Al wiring film using the same,and electronic components comprising the Al wiring film such assemiconductor elements, liquid crystal display devices, surface acousticwave devices or the like.

BACKGROUND ART

Recently, semiconductor industry typical in LSI is rapidly advancing. Insemiconductor elements such as DRAMs, as higher integration andreliability advance, accuracy required for fine machining is alsogetting higher and higher. Further, for also sputtering targets beingemployed in forming wiring or the like, a more homogeneous metalliclayer is demanded to form.

Among various kinds of metals for formation of the wiring, aluminum (Al)is attracting attention as formation material of low resistance wiring.Al is also expected as a wiring film being used as gate lines and signallines of a TFT drive type liquid crystal display device (LCD). This isbecause as the size of LCD screen becomes larger, the wiring film oflower resistance is in demand. For instance, a large LCD of such as morethan 10 inches necessitates the wiring of lower resistance of 10 μΩ cmor less.

Due to the Al wiring, the low resistance wiring can be realized.However, the Al film, due to heating at approximately 673K during heattreatment after CVD processing or wiring formation, generatesprotrusions called as hillock. This is because in the course of stressrelease of the Al film due to heating, Al atoms diffuse to generate theprotrusions accompanying the diffusion of the Al atoms. Suchprotrusions, when generated in the Al wiring, adversely affect on thelater process to cause problems.

Thereupon, it is tried to add a slight amount of metallic elements suchas Cu, Si, Pd, Ti, Zr, Hf, Nd and Y to the Al wiring (Japanese PatentLaid-Open Publication No. HEI 5-335271). Specifically, these metallicelements are added to an Al target itself. Such metallic elements asmentioned above, forming an intermetallic compound with Al, function astrapping material of Al. Thereby, the aforementioned hillocks aresuppressed from forming. In forming Al wiring for highly integratedsemiconductor elements and large size LCDs, the Al alloy target thatcontains a slight amount of such a metallic element is in use.

Now, as higher integration, higher reliability and higher functionalityof electronic devices such as semiconductor elements proceed, thestructure thereof has become more complicated. As a result of this, amulti level interconnection structure has come to be adopted.Accordingly, further technological innovation is required in finemachining technology. In addition to the wiring, further improvement ofreliability and longevity are in demand. For such purposes, sputteringfilms of high denseness and high orientation are in demand. Since suchsputtering films are difficult to obtain by use of the existing generalsputtering methods, new sputtering methods such as long throw sputteringor reflow sputtering are being adopted.

In sputtering by the general sputtering method, when segregation orinternal defect exists in a target, dust or splash may occur due to anextraordinary electric discharge or the like. These cause defects duringformation of DRAMs or TFT elements. There, investigation and elucidationof mechanism causing the dust or splash is in advance, and at the sametime, development of preventive measure is also in progress. Someresults are being obtained.

However, in the new sputtering methods such as the aforementioned longthrow sputtering or reflow sputtering, higher power or highertemperature than ever is being advanced. Accordingly, thermal influenceupon a target is becoming more than ever. In the long throw sputteringor reflow sputtering, the thermal influence on the target reaches up tofor instance approximately 500° C.

When forming, due to the long throw sputtering or reflow sputteringexposing the target to such severe conditions as mentioned above, an Alwiring film with an Al alloy target including a slight amount ofmetallic elements such as Cu, Si, Nd, Y or the like, lots of defectmodes that have never been ascertained are found to occur. That is,there occurs lots of giant dust particles having a size such large asfrom 100 to 5000 μm in the sputtered film to remarkably deteriorateyield of electronic devices such as DRAMs or TFT elements.

Further, in the long throw sputtering or reflow sputtering, there occura problem that concavities or holes of relatively larger size occur inthe sputtering films. These concavities or holes cause to deteriorateelectromigration resistance or stress migration resistance. Accordingly,the yield of electronic devices such as DRAMs or TFT elements isdeteriorated.

The existing dust preventive measure can not prevent the aforementionedgiant dust particles or relatively large size concavities fromoccurring. Accordingly, sounder fine wiring networks are in demand to beformed by use of the long throw sputtering or reflow sputtering.

Further, in the Al wiring (Al alloy wiring) including a slight amount ofthe aforementioned metallic elements, due to the intermetallic compoundformed between Al and an added element, Al can be suppressed fromdiffusing. However, there is a problem that a generated intermetalliccompound can adversely affect on etching property of the Al wiring. Thatis, when dry etching such as CDE (Chemical Dry Etching) or RIE (ReactiveIon Etching), or wet etching is applied to the Al wiring film thatcontains an intermetallic compound, the intermetallic compound causeinsoluble remains called as residue. This is largely detrimental informing the fine wiring network.

From the above, in the Al target and Al wiring that are employed forforming the low resistance wiring, it is demanded to suppress thediffusion of Al due to the heating after film formation to prevent thehillock or the like from occurring. In addition to this, it is demandedfor the residue also to be suppressed during etching.

An object of the present invention is to provide a sputtering targetthat enables to suppress new defect modes (giant dust particles or largeconcavities) from occurring. The new defect modes occur in particular,when the new sputtering methods such as long throw sputtering or reflowsputtering are employed. Further, the object includes, due to the use ofsuch sputtering target, to provide Al wiring films that are excellent inhillock resistance and formation property of fine wiring network, andelectronic components using such Al wiring films.

Further, another object of the present invention is to provide asputtering target that can form with reproducibility Al wiring films oflow resistance that are capable of preventing etching residue as well ashillock from occurring. Further, the object includes, by employing suchsputtering target, to provide Al wiring films excellent in hillockresistance and formation property of fine wiring network, and electroniccomponents employing such Al wiring films.

DISCLOSURE OF THE INVENTION

A first invention of the present application enables, throughelucidation of reasons why to cause giant dust particles in the newsputtering method such as long throw sputtering or reflow sputtering, tosuppress giant dust particles or the like from occurring. The firstinvention, by stipulating the degree of dispersion of added elements ina sputtering target with the mapping of EPMA (Electron Probe X-rayMicroanalyzer) analysis, suppresses the giant dust particles fromoccurring.

A sputtering target of the first invention consists essentially of 0.1to 50% by weight of at least one kind of element that forms anintermetallic compound with Al, and the balance of Al. Here, the elementthat forms the intermetallic compound is uniformly dispersed in thetarget texture, and, in a mapping of EPMA analysis, a portion of whichcount number of detection sensitivity of the element is 22 or more isless than 60% by area ratio in a measurement area of 20×20 μm.

The other sputtering target of the first invention consists essentiallyof 0.1 to 50% by weight of at least one kind of element selected from agroup consisting of Cu, Si, Sc, Y, La, Ce, Nd, Sm, Gd, Tb, Dy, Er, Pt,Ir, Ru, Pd, Ti, Zr, V, Nb, Ta, Fe, Ni, Cr, Mo, W, Mn, Tc, Re and B, andthe balance of Al. Here, the element is uniformly dispersed in thetarget texture, and, in the mapping of EPMA analysis, a portion of whichcount number of detection sensitivity of the element is 22 or more isless than 60% by area ratio in a measurement area of 20×20 μm.

The sputtering target of the first invention is further characterized inthat, in the aforementioned mapping of EPMA analysis, a portion of whichcount number of the aforementioned element that forms the intermetalliccompound or the element selected from the aforementioned group is 22 ormore is less than 10% by area ratio in a measurement area of 200×200 μm.

An Al wiring film of the first invention is characterized in that the Alwiring film is formed by use of the aforementioned sputtering target.The electronic component of the first invention comprises theaforementioned Al wiring film. As concrete examples of the electroniccomponents, semiconductor elements, liquid crystal display devices,surface acoustic wave devices or the like can be cited.

In the new sputtering method such as long throw sputtering or reflowsputtering, higher power and higher temperature more than ever are inadvance. Accordingly, thermal influence upon the target becomes morethan ever (for example, approximately 500° C.). Accordingly, thetemperature of the sputtering target surface during sputtering becomeshigher more than ever. Thereby, free energy of atoms constituting thetarget becomes large.

Accompanying such phenomena, the added element seeks for a stable areato precipitates at the grain boundary. Due to the precipitation of theadded element, there occurs a large difference of the sputtering ratebetween the grain boundary and the interior of the grain to result infor only the interior portion of the grain to locally remain.Accordingly, on the surface of the target large unevenness is generated.When the sputtering is continued on in such a state, the reboundedsputtered particles begin sticking on the generated projections.Thereby, the projections become gigantic in the size thereof. Suchprojections fly off the sputtering target as a mass, thereby the giantdust particles stick on the substrate.

As mentioned above, due to an increase of thermal influence on thetarget, the added element precipitates at the grain boundary to generatethe giant dust particle. The more non-uniform the initial state ofdispersion is, that is the more segregated the added elements are, themore remarkable the precipitation of the added element becomes.

There, in the sputtering target of the first invention, the dispersiondegree of the added element, in the mapping of EPMA analysis, isstipulated so that a portion where the count number of detectionsensitivity of the added element is 22 or more is less than 60% by arearatio in a measurement area of 20×20 μm. By satisfying such a state ofdispersion, the precipitation of the added elements can be suppressed,thereby the giant dust particles can be suppressed from occurring.

According to the wiring film formed by use of the sputtering method suchas long throw sputtering or reflow sputtering with the aforementionedfirst sputtering target, the giant dust particles can be suppressed fromoccurring. Accordingly, the product yield can be remarkably improved. Inaddition to this, based on the sputtering methods as described above,the Al wiring film of high denseness and high orientation can beprovided.

A second invention of the present application, through elucidation ofreasons why to cause the relatively large concavities or holes in thenew sputtering method such as long throw sputtering or reflowsputtering, enables to suppress the giant dust particles and relativelylarge concavities and holes both based on the giant dust particles fromoccurring. In the second invention, by stipulating the dispersion degreeof impurity elements such as Cr, Fe, C or the like in a target with themapping of EPMA analysis, giant dust particles and relatively largeconcavities and holes both due to the giant dust particles aresuppressed from occurring.

In a sputtering target in the second invention, a first mode is asputtering target consisting essentially of 0.1 to 50% by weight of atleast one kind of element that forms an intermetallic compound with Al,and the balance of Al. Cr contained in the aforementioned target ischaracterized in that, in the mapping of EPMA analysis, a portion ofwhich count number of detection sensitivity of Cr is 33 or more is lessthan 60% by area ratio in a measurement area of 20×20 μm.

A second mode is a sputtering target consisting essentially of 0.1 to50% by weight of at least one kind of element that forms anintermetallic compound with Al, and the balance of Al. Fe contained inthe target is characterized in that, in the mapping of EPMA analysis, aportion of which count number of detection sensitivity of Fe is 20 ormore is less than 60% by area ratio in a measurement area of 20×20 μm.

A sputtering target of a third mode is a sputtering target consistingessentially of 0.1 to 50% by weight of at least one kind of element thatforms an intermetallic compound with Al, and the balance of Al. Ccontained in the aforementioned target is characterized in that, in themapping of EPMA analysis, a portion of which count number of detectionsensitivity of C is 55 or more is less than 60% by area ratio in ameasurement area of 20×20 μm.

The sputtering target of the second invention is further characterizedin that, in each mapping of EPMA analysis of Cr, Fe and C as impurityelement, a portion of which count number is more than the stipulated onefor each element (the count numbers of Cr: 33, Fe: 20, and C: 55) isless than 10% by area ratio in a measurement area of 200×200 μm.

An Al wiring film in the second invention is one that is formed bysputtering the aforementioned sputtering target. An electronic componentin the second invention is one that comprises the aforementioned Alwiring film. As concrete examples of the electronic components,semiconductor elements, liquid crystal display devices, surface acousticwave devices or the like can be cited.

In the new sputtering methods such as long throw sputtering or reflowsputtering method, as explained above, the temperature of the targetsurface becomes higher than ever during sputtering, thereby the freeenergy of atoms constituting the target becomes larger. Accompanyingsuch phenomena, the impurity elements contained in the target, inparticular Cr, Fe and C seek a stable area to precipitate at the grainboundary. Due to precipitation of these impurity elements, there occursa large difference in the sputtering rates between the grain boundaryand the inside of the grain. Thereby, only the interior of the grainlocally remains on the target surface to form a large unevennessthereon.

In a state where the large unevenness is formed on the target surface,when the sputtering is further continued on, to the projections formed,sputtered particles rebound to stick to form giant projections. Thesegiant projections fly off the target as a mass to stick on a substrateas giant dust particles. When such giant dust particles containing theimpurity elements stick to the substrate, a mode of growth of the filmchanges only there from others to cause a difficulty in stacking theconstituent atoms thereon. Thus, concavities and holes large relative tothe sputtering film are formed.

As thermal influence on the target increases, the impurity elements suchas Cr, Fe and C precipitate at the grain boundary to generate relativelylarge concavities and holes and the giant dust particles causing these.The less uniform the initial state of dispersion of the impurity elementis, in other words, the more segregated the impurity in the target is,the more conspicuous the precipitation of the impurity element becomes.

There, in the sputtering target of the second invention, the degrees ofdispersion of Cr, Fe and C, with the mappings of the EPMA analysis, arestipulated in the range as described above. By satisfying suchdispersion states of Cr, Fe and C, these impurity elements can besuppressed from precipitating. As a result, the relatively largeconcavities and holes and the giant dust particles causing these can besuppressed from occurring.

With the second sputtering target such as described above, Al wiringfilms are formed by use of long throw sputtering or reflow sputtering.According to thus formed Al wiring films, the relatively largeconcavities or holes, being suppressed from occurring, can remarkablyimprove the product yield. In addition to this, due to theaforementioned sputtering method, the Al wiring films or the like ofhigher denseness and orientation can be provided.

The sputtering targets in the first and second inventions are notrestricted in application to the long throw sputtering and reflowsputtering, but can be applied even in the existing general sputteringmethod. The same can be said with the Al wiring films of the first andsecond inventions.

In a third invention of the present application, occurrence of etchingresidue of an Al wiring film containing an element that forms anintermetallic compound and deterioration of finely etching property canbe suppressed from occurring by incorporating Ar or Kr in the Al wiringfilm.

A sputtering target in a third invention consists essentially of atleast one kind of element that forms an intermetallic compound with Alin the range of from 0.1 to 20% by weight, at least one kind of elementselected from Ar and Kr by 5% by weight or less (not including 0% byweight), and the rest of Al.

Another sputtering target in the third invention consists essentially ofat least one kind of element selected from Y, Sc, La, Ce, Nd, Sm, Gd,Tb, Dy, Er, Th, Si, Sr, Ti, Zr, V, Nb, Ta, Mn, Tc, Re, Cu and B in therange of from 0.1 to 20% by weight, at least one kind of elementselected from Ar and Kr by 5% by weight or less (not including 0% byweight), and the rest of Al.

An Al wiring film in the third invention consists essentially of atleast one kind of element that forms an intermetallic compound with Alin the range of from 0.1 to 20% by weight, at least one kind of elementselected from Ar and Kr by 5% by weight or less (not including 0% byweight), and the rest of Al. Further, the Al wiring film ischaracterized in that it is formed by use of the aforementionedsputtering target of the third invention. An electronic component in thethird invention is characterized in that the electronic componentcomprises the aforementioned Al wiring film. As the concrete examples ofthe electronic components, liquid crystal display devices, semiconductorelements, surface acoustic wave devices or the like can be cited.

In the third invention, to Al, together with an element that forms anintermetallic compound with Al such as Y, a slight amount of at leastone kind of element selected from Ar and Kr is added. In the sputteringfilms obtained by use of such an Al target, there exist an intermetalliccompound or an element that forms an intermetallic compound both poor inetching workability. However, Ar and Kr enhance their reactivity duringetching. Further, Ar and Kr cause the intermetallic compound and theelement themselves that forms an intermetallic compound that are poor inetching workability to finely and uniformly precipitate inside the grainof Al and at the grain boundary thereof.

Thus, Ar and Kr enhance the etching property (reactivity) of theintermetallic compound and the element itself that forms anintermetallic compound, and by finely and uniformly precipitating these,remarkably improve the etching property of the sputtered film, furthercan suppress the dust particles from occurring during sputtering. Theadded Ar or Kr does not adversely affect on suppression of diffusion ofAl. Accordingly, the added element that forms an intermetallic compoundcan effectively prevent the hillock from occurring. Accordingly, the Alwiring films excellent in hillock resistance and in properties offorming fine wiring networks can be formed with reproducibility.

EMBODIMENTS FOR PRACTICING THE PRESENT INVENTION

In the following, modes for practicing the present invention will beexplained.

A sputtering target of the present invention comprises at least one kindof element selected from a group of Cu, Si, Sc, Y, La, Ce, Nd, Sm, Gd,Tb, Dy, Er, Pt, Ir, Ru, Pd, Ti, Zr, V, Nb, Ta, Fe, Ni, Cr, Mo, W, Mn,Tc, Re and B in the range of 0.1 to 50% by weight, and the restessentially consisting of Al. The element being added to the target ispreferable to be an element that forms an intermetallic compound withAl.

As the element that forms an intermetallic compound, various kinds ofmetallic elements, if can form an intermetallic compound with Al, can beemployed. In concrete, Cu, Si, Cr, Ni, Pt, Ir, Ta, W, Mo, Nb and Re, andrare earth elements such as Y, Gd, Nd, Dy, Sm, Er and the like can becited. In the sputtering target of the present invention, other thanthese elements that form an intermetallic compound, as cited above asthe element group, an element that does not form an intermetalliccompound can be adopted as an element being added.

Among these various kinds of elements being added, when the sputteringtarget is employed for forming the wiring of a semiconductor element,such materials of high conductivity as Cu, W, Mo, Ru, Pt or the like canbe preferably employed. Cu is particularly preferable. These areeffective in forming ultra-fine wiring of for instance a wiring width ofsuch as 0.25 μm or less. Further, when the sputtering target is employedfor forming the wiring for a liquid crystal display device, as theelement being added, rare earth elements such as Y, Gd, Nd, Dy, Sm andEr are preferably employed.

The sputtering target of the present invention is preferable to includeat least one kind of element that forms an intermetallic compound withAl. The aforementioned element forms an intermetallic compound with Al(for instance, Al₃Cu for copper and Al₃Y for Y). Accordingly, when theobtained sputtered film is exposed to heat treatment, Al is suppressedin diffusing. As a result, the hillock or the like can be prevented fromoccurring.

Solubility of an element that is used to form an intermetallic compoundis preferable to be 1.0% by weight or less with respect to Al. When thesolubility of the element being used exceeds 1.0% by weight with respectto Al, there is a risk that sufficient suppression effect against thehillock due to formation of the intermetallic compound with Al can notbe obtained. In addition, resistivity may increase.

The element that forms an intermetallic compound is contained in asputtering target in the range of 0.1 to 50% by weight. When the contentof the element that forms an intermetallic compound is less than 0.01%by weight, the aforementioned effect of suppressing the hillock can notbe sufficiently exhibited. In contrast, when the content exceeds 50% byweight, the intermetallic compound increases resistance of the sputteredfilm, that is the Al wiring film. The more preferable amount of additionis in the range of 0.1 to 10% by weight, being further preferable to bein the range of 0.5 to 1.5% by weight.

When the sputtering target is employed in forming wiring for a liquidcrystal display device, the element that forms an intermetallic compoundis preferable to be contained in the range of 0.1 to 20% by weight inthe sputtering target. When the content of the element that forms anintermetallic compound is less than 0.1% by weight, the aforementionedhillock suppression effect can not be sufficiently exhibited. Incontrast, when the content exceeds 20% by weight, the intermetalliccompound increases the resistance of the obtained sputtered film, thatis the Al wiring film, and remains as residue during dry etching or wetetching. More preferable addition amount is in the range of from 1 to15% by weight.

In the sputtering target of the present invention, the aforementionedadded element is uniformly dispersed in the texture of the target. Thedispersion degree of the added element is stipulated by use of themapping of EPMA (Electron Probe X-ray Microanalyzer) analysis. That is,in the mapping of EPMA analysis of the added element such as the elementthat forms an intermetallic compound, a portion of which count number ofdetection sensitivity of the added element is 22 or more is stipulatedto be 60% or less by area ratio in a measurement area of 20×20 μm. Theportion of which count number of the element that forms an intermetalliccompound is 22 or more is more preferable to be less than 40% by arearatio in a measurement area of 20×20 μm.

Now, the mapping of EPMA analysis in the present invention is measuredunder the conditions shown in Table 1.

TABLE 1 Name of Apparatus Electron Probe X-ray Microanalyzer by JEOL;Type JXA-8600M ACCEL Voltage 15 (kV) Probe Current 2 × 10⁻⁷ (A) DualTime 20 (ms) Scan STAGE Measurement Range · X Axis: 200 (μm) · 1 (μm)Measurement Pitch Y Axis: 200 (μm) · 1 (μm)

According to the EPMA analysis, the state of dispersion of an element ina plane can be accurately measured. At this time, a portion where countnumber of detection sensitivity is 22 or more indicates an area where anelement being measured is distributed much. That is, a sputtering targetof the present invention in which, in the mapping of EPMA analysis ofthe element that forms an intermetallic compound, in a measurement areaof 20×20 μm, a portion of which count number of detection sensitivity is22 or more is stipulated to be less than 60% can be one in which theelement that forms an intermetallic compound is remarkably uniformlydispersed.

By satisfying such state of dispersion of the element that forms anintermetallic compound, even when a new sputtering method such as longthrow sputtering or reflow sputtering is applied, the giant dustparticles can be suppressed from occurring. Even when an ordinarysputtering method is employed, by setting a portion of which countnumber of the element that forms an intermetallic compound is 22 or morein a measurement area of 20×20 μm at less than 60% by area ratio, thedust particles can be suppressed from occurring.

When a sputtering method such as long throw sputtering or reflowsputtering is employed, the thermal influence on a sputtering targetbecomes more than ever (for instance, approximately 500° C.).Accordingly, the free energy of atoms constituting the target becomeslarge. Accompanying such phenomenon, the element that forms anintermetallic compound or the like as an added element seeks a stablearea to precipitate at grain boundary. Thereby, the sputtering rates aremade largely different between the grain boundary and the interior ofthe grain. Accordingly, only the interiors of the grains remain locally,in addition to this giant projections are formed on the surface of thetarget. These fly off the surface of the target as a mass and stick on asubstrate as giant dust particle.

The more non-uniform an initial dispersion state of the added elementthat causes giant dust particles is, in other words, the more segregatedthe added element is, the more conspicuous the precipitation thereofbecomes. That is, in the mapping of the EPMA analysis, in a measurementarea of 20×20 μm, if a portion of which count number of detectionsensitivity of the added element is 22 or more exceeds 60% by arearatio, the giant dust particles are enhanced in occurrence to result ina remarkable decrease of the yield.

A portion of which count number of detection sensitivity of the addedelement such as an element that forms an intermetallic compound is 22 ormore is preferable to be less than 10% by area ratio in an area of200×200 μm that is an ordinary observation area in EPMA observation.When in the EPMA mapping, in a measurement area of 200×200 μm, a portionof which count number is 22 or more exists 10% or more, similarly thegiant dust particles are promoted in occurrence to result in aremarkable decrease of the yield. A portion where count number of theelement that forms an intermetallic compound is 22 or more is morepreferable to be less than 5% in a measurement area of 200×200 μm.

Thus, the sputtering target of the present invention has anapproximately uniform texture over the entire target. Accordingly, thegiant dust particles can stably and with reproducibility be suppressedfrom occurring.

The sputtering target of the present invention is further preferable forCr, Fe and C contained in the target as impurity elements to beuniformly dispersed. The dispersion degree of these elements can besimilarly stipulated with the mappings of the EPMA analysis. The mappingof the EPMA analysis is measured under the conditions shown in Table 1.

That is, in each mapping of EPMA analysis of Cr, Fe and C, in ameasurement area of 20×20 μm, the portion where the count number ofdetection sensitivity is 33 or more for Cr, 20 or more for Fe, and 55 ormore for C respectively is stipulated to be 60% or less by area ratio.Cr, Fe and C each tends to precipitate at the grain boundary of an Alalloy target and is likely to cause relatively large concavities andholes (and giant dust particles that cause the concavities and holes) inthe sputtered film.

There, for Cr, in the mapping of EPMA analysis, in a measurement area of20×20 μm, a portion of which count number of detection sensitivity is 33or more is stipulated to be less than 60% by area ratio. For Fe,similarly a portion of which count number of detection sensitivity is 20or more is stipulated to be less than 60% by area ratio. For C,similarly a portion of which count number of detection sensitivity is 55or more is stipulated to be less than 60% by area ratio. Thus stipulatedCr, Fe and C are restricted to the impurity elements in the target, andCr and Fe, when employed as the element that forms an intermetalliccompound, are not included therein.

According to the EPMA, a state of dispersion of an element in a planecan be accurately measured. A portion of larger count number ofdetection sensitivity at this time shows an area abundant indistribution of an element to be measured. That is, in the mapping ofEPMA analysis of Cr, Fe and C each, in a measurement area of 20×20 μm,the portion of which count number of detection sensitivity is 33 ormore, 20 or more, and 55 or more, respectively, is stipulated to be lessthan 60%. The sputtering target of the present invention can be said onein which the unavoidable impurity elements are uniformly dispersed.

As mentioned above, by uniformly dispersing Cr, Fe and C, even when anew sputtering method such as long throw sputtering or reflow sputteringis applied, the giant dust particles and relatively large concavitiesand holes both due to the giant dust particles can be suppressed fromoccurring. Even in an ordinary sputtering method, the dust particlesalso can be suppressed from occurring.

When the sputtering method such as long throw sputtering or reflowsputtering is applied, as mentioned above the free energy of atomsconstituting the target becomes larger. Accompanying such phenomena, Cr,Fe and C contained in the target seek a stable area to precipitate atthe grain boundary. Thereby, sputtering rates become largely differentbetween the grain boundary and the interior of the grain. Accordingly,only the interior portions remain locally to result in large projectionsformed on the surface of the target. These fly off the target as a massto stick on the substrate as the giant dust particles.

When such a giant dust particle sticks on a substrate, only there themode of growth of the film changes to cause difficulties in furtherstacking the atoms constituting the film thereon. Accordingly,relatively large concavities and holes are formed in the sputtered film.Precipitates of the respective elements causing the relatively largeconcavities and holes become more conspicuous as the initial state ofdispersion thereof is less uniform, in other words, as each element ismore segregated. That is, in the mapping of the EPMA analysis of Cr, Feand C each, in a measurement area of 20×20 μm, when each portion ofwhich count number of detection sensitivity is 33 or more, 20 or moreand 55 or more occupies 60% or more by area ratio, the giant dustparticles and relatively large concavities and holes caused by the giantdust particles are promoted in occurring to result in a large decreaseof the yield of the sputtered films (Al wiring films).

The portion where the count number of detection sensitivity of Cr, Feand C each exceeds each stipulated value, that is, the portion of 33 ormore for Cr, 20 or more for Fe and 55 or more for C, is preferable toexist less than 10% by area ratio in a measurement area of 200×200 μm.In the mapping of EPMA analysis, in a measurement area of 200×200 μm,when the portion of which count number exceeds the each stipulated valueexist 10% or more by area ratio, similarly the giant dust particles arepromoted in occurring to result in a conspicuous decrease of the yield.The portion where the count number of the each element exceeds the eachstipulated value is further preferable to be less than 5% in the eachmeasurement areas of 200×200 μm.

Thus, the sputtering target of the present invention has anapproximately uniform texture including impurity elements such as Cr, Feand C throughout an entire target area. Accordingly, the occurrence ofthe giant dust particles and the relatively large concavities and holescaused by the giant dust particles can be suppressed with stability andreproducibility. In the sputtering target of the present invention,though Cr, Fe and C are stipulated by the states of dispersion as theimpurity elements, it is beyond question that the amount of the impurityelements is better to be essentially low. As a specific amount (totalamount) of the impurity elements, 1% by weight or less is preferable. Cras an impurity element is preferable to be 0.1% by weight or less, Fe is0.1% by weight or less, and C is 0.05% by weight or less.

The sputtering targets of the present invention such as described abovecan be produced by use of various kinds of known production methods suchas atmospheric fusion method, vacuum fusion method, quench hardeningmethod (spray forming method), powder metallurgy method or the like.However, the following production process is particularly preferablyapplied.

First, high purity Al (for instance, purity of 99.99% or higher) iscompounded with a prescribed amount of an element being added to producean ingot by use of for instance continuous casting method (atmosphericfusion). Here, when Al alloy raw material is atmosphere fused, it ispreferable for the molten metal to be bubbled by the inert gas such asAr. The bubbling due to Ar or the like not only contributes in simplydecreasing the amount of the impurity elements but also has an effect ofuniformly dispersing Cr, Fe and C that tend to unavoidably remain.Thereby, even if the content is approximately equal with that of forinstance the vacuum fusion, Al alloy raw material of more uniformdispersion can be obtained. A size of billet is preferable to be adiameter in the range of from approximately 100 to 500 mm.

The aforementioned billet, after primary heat treatment, is cooled. Theprimary heat treatment is preferable to implement at a temperature offrom 450 to 600° C. for more than 5 hours. By such heat treatment, theadded elements and impurity elements can be homogenized. The coolinghere can be any one of air-cooling, furnace cooling, and quenching.

Next, plastic working such as forging or rolling is implemented. In theplastic working due to the forging, it is preferable to give a workingrate in the range of from 30 to 80%. In the plastic working due to therolling, the working rate is preferable to be in the range of from 40 to99%. According to the plastic working of such working rates, due tothermal energy applied to the ingot during the treatment, the addedelements such as elements that forms an intermetallic compound, inaddition to these impurity elements such as Cr, Fe and C can beuniformly dispersed. In addition, the thermal energy plays a roll ofcoordinating the arrangement of crystal lattice to effectively work inremoving minute internal defects.

Thereafter, as a secondary heat treatment, heating is implemented at atemperature of from 200 to 500° C. for more than 10 min. Thus obtainedraw material is machined to produce a sputtering target of a prescribedsize.

The sputtering target of the present invention can contain, in additionto the elements being added such as elements that form an intermetalliccompound, at least one kind of element selected from Ar and Kr in therange of 5% by weight or less (not including 0% by weight). Ar and Krenhance reactivity of the intermetallic compound and the element itselfthat form an intermetallic compound during etching. That is, in etchingthe intermetallic compound or the element that forms the intermetalliccompound, Ar and Kr exhibit a catalytic effect. Further, Ar or Kr actseffectively in micro-precipitation of the intermetallic compound or theelement itself that forms the intermetallic compound. Accordingly theintermetallic compound or the element itself that forms theintermetallic compound in the obtained sputtered film (Al wiring film)can be finely and uniformly precipitated inside Al grains or at thegrain boundaries of the Al.

Thus, etching reactivity of the intermetallic compound or the elementthat forms the intermetallic compound in the Al wiring film is enhanceddue to Ar or Kr. In addition to this, the intermetallic compound or theelement itself that forms the intermetallic compound can be finely anduniformly precipitated in the Al wiring film due to Ar or Kr. Thereby,the etching property of the entire Al wiring film can be remarkablyimproved. Accordingly, in forming a wiring network in the Al wiring filmby use of the dry etching method or the like, the etching residue can besuppressed in occurrence.

Further, the fine and uniform precipitation of the intermetalliccompound and the element itself that forms the intermetallic compoundcan also suppress the dusts from occurring during sputtering.Accordingly, the Al wiring film formed by the use of the sputteringtarget of the present invention is excellent in forming a fine wiringnetwork.

The content of at least one kind of element selected from Ar and Kr isin the range of 5% by weight or less with respect to the sputteringtarget. When the content of Ar or Kr exceeds 5% by weight, excess Ar orKr precipitates at the grain boundary of Al or the like to result in adecrease of etching property to the contrary. The more preferablecontent of Ar or Kr is in the range of from 1 ppb by weight to 0.1% byweight, the further preferable content being in the range of from 1 to100 ppm by weight.

A production method of a sputtering target containing Ar or Kr is notparticularly restricted, and a known production method such as fusionmethod or powder metallurgy method can be employed.

When the fusion method is employed, first a prescribed amount of anelement that forms an intermetallic compound such as Y is compoundedwith Al, the compounded body being induction fused in a vacuum. At thistime, by bubbling the molten metal with Ar or Kr, a prescribed amount ofAr or Kr can be contained in the molten metal. Thus, an ingot containingan element that forms an intermetallic compound such as Y and at leastone kind of element selected from Ar or Kr is prepared.

When powder metallurgy method is applied, a prescribed amount of anelement that forms an intermetallic compound such as Y is compoundedwith Al, the compounded body being treated by atmospheric sintering, hotpressing, hipping or the like to obtain a sintered body. At this time,by implementing a sintering process in an atmosphere including Ar or Kr,a sintered body that includes, together with the element that forms anintermetallic compound such as Y, Ar or Kr can be obtained.

Among the aforementioned various production methods, the fusion methodis suitable because it can produce a product of relatively high densityand high purity. Typical examples of Ar and Kr amounts in Al alloys areshown in Table 2 for various methods. The Ar and Kr amounts are measuredby use of gas analysis method (infrared absorption method).

TABLE 2 Amount of Ar in Amount of Kr in Al Alloy Al Alloy ProductionMethod (% by weight) (% by weight) Fusion Method 0.082 0.002 Hot Press0.003 0.023 Spray Forming 2.21 0.121 HIP 0.02 0.0083

The ingot obtained by the fusion method or the sintered body obtained bythe powder metallurgy method undergoes hot working, cold working or thelike. In addition, as the demands arise, recrystallization heattreatment or crystal orientation control is carried out to obtain anaimed sputtering target. The conditions for these are same with thosementioned above.

In the case of a target being a larger size, diffusion bonding or thelike may be implemented to form the target in a desired shape. However,when a target of larger size that is employed in forming larger sizeLCDs is produced, it is preferable to collectively produce by use offusion method from a view point of dust suppression during sputtering.Depending on the intended sputtering target, requirement on purity,texture, plane orientation or the like is different. Accordingly,corresponding to the aforementioned required characteristics, theproduction method can be properly adjusted.

The sputtering target of the present invention is bonded to a Cu backingplate to employ. In bonding a target and a backing plate, brazing by useof at least one kind of In, Zn and Sn, or brazing material includingthese or diffusion bonding is adopted. In addition, instead of employinga separate backing plate, it can be an integrated sputtering target inwhich a backing plate portion is simultaneously formed during theproduction of the sputtering target.

The Al wiring film of the present invention, with the aforementionedsputtering target of the present invention, can be formed by use of, forinstance, long throw sputtering or reflow sputtering. The Al wiring filmof the present invention may be one that is formed by use of an ordinarysputtering method.

As mentioned above, according to the sputtering target of the presentinvention, giant dust particles and relatively large concavities orholes can be suppressed in occurrence. Accordingly, the product yield ofthe Al wiring films can be remarkably improved. In addition, due to theaforementioned new sputtering methods, dense and highly oriented Alwiring films can be provided. Further, due to the added element thatforms an intermetallic compound, hillock due to diffusion of Al can beeffectively prevented from occurring.

Such Al wiring films of the present invention can be applied in variouskinds of electronic components. As the electronic components of thepresent invention, semiconductor elements in which the present Al wiringfilms are applied in gate lines, signal lines or the like thereof can becited. The present invention exhibits its effect in particular insemiconductor elements such as ULSI DRAM(wiring width: 0.25 to 0.18 μm)of such a high integration degree as 64 Mbit. The Al wiring films of thepresent invention can be employed, without restricting to thesemiconductor elements, in various kinds of electronic components suchas liquid crystal display devices, surface acoustic wave devices,thermal print heads or the like.

The Al wiring films of the present invention obtained by sputtering asputtering target containing Ar or Kr are suitable for the wiring ofliquid crystal display devices. In such Al wiring film, an element suchas Y that forms an intermetallic compound or an intermetallic compoundbetween the element and Al is finely and uniformly precipitated.

In such Al wiring film, simultaneously added Ar or Kr enhances etchingof the element that forms an intermetallic compound. In addition, theelement itself that forms an intermetallic compound and theintermetallic compound thereof with Al, due to the effect of Ar or Kr,are finely and uniformly precipitated within the grains or at grainboundaries of Al. Thereby, etching property of the Al wiring films canbe remarkably improved. Further, since dust particles can be suppressedin occurrence during sputtering, fine dust particles can be also largelyreduced.

Further, the diffusion of Al that accompanies heating due to the heattreatment or the like can be suppressed from occurring due to theformation of an intermetallic compound between an element that forms anintermetallic compound and Al. Accordingly, hillocks due to thediffusion of Al can be effectively prevented from occurring.Accordingly, such Al wiring films are excellent in hillock resistanceand there is no chance of the hillock affecting adversely on the laterprocess. Further, such Al wiring films are excellent in fine wiringnetwork formation.

Such Al wiring films of the present invention can be applied in variouskinds of electronic components. In specific, such as gate lines andsignal lines of a liquid crystal display device (LCD), wiring networksof a semiconductor element such as ULSI or VLSI, wiring patterns of asurface acoustic wave device or a thermal print head or the like, wiringof various kinds of electronic components can be cited. In theelectronic components of the present invention, thus the Al wiring filmsof the present invention are employed. These are particularly effectivein LCD panels of larger screen size and higher definition and insemiconductor elements of finer pattern.

Next, specific embodiments of the present invention will be explained.

Embodiment 1

First, 0.5% by weight of Cu with respect to Al is compounded with Al. Aningot of intended composition is produced by use of continuous castingmethod (atmospheric fusion) . The ingot undergoes hot rolling, coldrolling and heat treatment. Thereafter, by machining the ingot an Alalloy target of a diameter of 320 mm and a thickness of 20 mm isprepared. At this time, by varying each condition of hot rolling, coldrolling and heat treatment, 10 pieces of Al alloy targets different indispersion degree of Cu are obtained. The dispersion degree of Cu ismeasured and evaluated by use of the EPMA apparatus shown in theaforementioned Table 1.

The dispersion degree of Cu is shown in Table 3. The dispersion degreeof Cu, in the mapping of EPMA analysis, shows an area ratio (%) of aportion of which count number of detection sensitivity is 22 or more ina measurement area of 20×20 μm, and an area ratio (%) of a portion ofwhich count number is 22 or more in an observation area of 200×200 μm.

With thus obtained 10 pieces of Al alloy targets, by use of the existingsputtering method, on each Si substrate of a diameter of 8 inches, an Alalloy film of a thickness of 300 nm is formed. Sputtering conditions areas follows: back pressure of 1×10⁻⁵ Pa; DC output of 1.5 kW; andsputtering time of 1 min. Number of dust particles in each Al alloy filmthus obtained is measured by use of a dust counter (WM-3). The number ofdust particles is measured for each size range thereof. Thesemeasurement results are shown in Table 3.

TABLE 3 Dispersion Degree of Cu Dust Size Sample 20 × 200 × Under 0.2 to0.3 to Over No. 20 μm 200 μm 0.2 μm 0.3 μm 100 μm 100 μm 1 40.3 2.7 7 21 0 2 15.2 0.5 11 3 0 0 3 7.8 1.3 9 3 0 0 4 1.5 3.6 5 4 2 0 5 22.7 4.1 22 1 0 6 69.8 69.9 98 45 23 89 7 88.3 60.8 79 52 26 49 8 76.8 54.2 88 4831 30 9 90.1 79.3 92 56 33 89 10 84.3 59.5 83 61 29 73

As obvious from Table 3, according to the sputtering targets of thepresent invention, the occurrence number of the dust is suppressed. TheAl alloy films formed by use of such sputtering targets can remarkablyimprove the products yield due to the decrease of the number of dust,and can provide wiring films of uniform texture.

Embodiment 2

With 10 pieces of Al alloy targets prepared in the embodiment, exceptfor changing the sputtering method to reflow sputtering, under identicalconditions as those of embodiment 1, Al alloy films are formed and thenumber of dust particles is similarly measured. The results are shown inTable 4.

TABLE 4 Dispersion Degree of Cu Dust Size Sample 20 × 200 × Under 0.2 to0.3 to Over No. 20 μm 200 μm 0.2 μm 0.3 μm 100 μm 100 μm 1 35.6 0.29 5 10 0 2 12.4 1.8 8 4 2 0 3 8.5 3.8 11 2 1 0 4 1.3 1.5 9 8 0 0 5 21.9 0.6 74 1 0 6 70.1 59.4 152 89 35 890 7 88.5 68.7 188 67 60 498 8 75.4 74.1232 82 51 730 9 89.8 87.3 132 95 63 1089 10 83.4 69.4 120 77 99 573

As obvious from Table 4, according to the sputtering targets of thepresent invention, the dust particles of a size of 0.3 μm or more arealso suppressed from occurring. In particular, the giant dust particlesthat cause problems in the reflow sputtering or the like are suppressedfrom occurring. The Al alloy films formed by use of such sputteringtargets can remarkably improve the product yield based on the decreaseof the dust number, and can provide the wiring films of uniform texture.

Embodiment 3

To Al, various kinds of elements (Si, Cr, Y, Ni, Nd, Pt, Ir, Ta, W andMo) are added with the respective compounding amounts shown in Table 5.The respective compounded bodies are treated by use of continuouscasting method (atmospheric fusion) to prepare ingots of intendedcompositions. Each of the ingots undergoes hot rolling, cold rolling andheat treatment. Thereafter, due to machining, Al alloy targets of adiameter of 320 mm and a thickness of 20 mm are prepared.

At this time, by selecting properly the respective conditions of hotrolling, cold rolling and heat treatment, the dispersion degree of theadded elements are controlled within the range stipulated by the presentinvention. The dispersion degrees of the respective added elements aremeasured similarly with embodiment 1.

With the respective Al alloy targets thus obtained, due to the reflowsputtering method, on each Si substrate of a diameter of 8 inches, an Alalloy film of a thickness of 300 nm is formed respectively. Thesputtering conditions are as follows; a back pressure of 1×10⁻⁵ Pa, a DCoutput of 1.5 kW and a sputtering time of 1 min. The dust particles inthus obtained Al alloy films each are measured similarly withembodiment 1. The results are shown in Table 5.

TABLE 5 Dispersion Degree of Added Element Dust Size Sample Composition20 × 200 × Under 0.2 to 0.3 to Over No. of Target 20 μm 200 μm 0.2 μm0.3 μm 100 μm 100 μm 1 Al-2 wt % Y 10.3 1.7 7 2 1 0 2 Al-3 wt % Ni 5.20.1 8 3 0 0 3 Al-0.8 wt % Ta 7.8 1.4 9 3 0 0 4 Al-0.5 wt % Si 1.5 2.5 54 2 2 5 Al-7 wt % Ir 32.7 1.2 2 0 1 0 6 Al-5 wt % Pt 9.8 0.9 8 4 0 1 7Al-0.01 wt % W 2.3 2.8 9 5 0 0 8 Al-0.8 wt % Mo 26.8 3.2 2 4 3 0 9 Al-25wt % Cr 19.1 3.1 9 5 4 0 10  Al-10 wt % Nd 3.2 2.3 4 1 2 3

As obvious from Table 5, according to the sputtering targets of thepresent invention, though the dust particles of a size of 0.3 μm or morecan be suppressed from occurring, also the giant dust particles thatcause problems particularly in the reflow sputtering are suppressed fromoccurring. The Al alloy films formed by the use of such sputteringtargets can remarkably improve the product yield due to the decrease ofthe number of dust particles and can provide the wiring films of uniformtexture.

Al wiring films obtained by sputtering the respective Al alloy targetsof the aforementioned embodiments 1 to 3 are used as Al wiring films ofsemiconductor elements, LCD panels and SAW devices. As a result,electronic components of high reliability can be obtained, respectively.

Embodiment 4

0.5% by weight of Cu with respect to Al is compounded with Al, theobtained compounded body being treated by use of the continuous castingmethod (atmospheric fusion) to prepare an ingot of an intendedcomposition. The atmospheric fusion is carried out while bubbling Ar.Thus obtained ingot undergoes a primary heat treatment, hot rolling,cold rolling and a secondary heat treatment, followed by machining toprepare Al alloy targets of a diameter of 320 mm and a thickness of 20mm.

At this time, by varying the respective conditions of fusion, hotrolling, cold rolling and heat treatments, a plurality of Al alloytargets of which dispersion degrees of Cr, Fe and C are different areobtained. The dispersion degrees of the respective elements are measuredand evaluated by use of the EPMA apparatus shown in Table 1.

The dispersion degree of each element is shown in Table 6. Thedispersion degree of each element is shown by the use of two area ratiosin the mapping of EPMA analysis. One is an area ratio (%) of a portionof which count number of detection sensitivity in a measurement area of20×20 μm is the value stipulated in the present invention or more, andthe other one is an area ratio (%) of a portion of which count number ofdetection sensitivity in an observation area of 200×200 μm is the valuestipulated in the present invention or more.

With each of thus obtained Al alloy targets, by use of reflowsputtering, on a Si substrate of a diameter of 8 inches, an Al alloyfilm of a thickness of 300 nm is formed, respectively. The sputteringconditions are as follows; a back pressure of 1×10⁻⁵ Pa, a DC output of1.5 kW and a sputtering time of 1 min. The dust particles in therespective Al alloy films thus obtained are measured by use of the dustcounter (WM-3). The number of dust particles is measured according tothe size ranges.

Next, photolithography is implemented to each of the aforementioned Alalloy films to form 30 fine lines of a width and a length of 2 μm and 2mm each for each Al alloy film. In order to evaluate reliability ofthese fine lines, a test current is flowed under conditions of a currentdensity of 10⁶ A/cm², a pass time of 200 hours and a wafer temperatureof 150° C. As a result of this, snapping rates (%) are obtained based onthe fine lines in which snapping occurred. The results are showntogether in Table 6.

TABLE 6 Number of Dust Dispersion Particle (dust Degree of particles ofEach Element each size/wafer) Sample Element 20 × 20 200 × under 0.3 toover Snapping No. contained μm 200 μm 0.3 μm 100 μm 100 μm Rate (%) 1 Cr25 3 8 11 0 3 2 Cr 35 11 7 12 5 10 3 Cr 82 21 11 10 8 40 4 Cr 75 45 9 1113 36 5 Fe 15 20 3 5 0 0 6 Fe 21 65 3 6 13 15 7 Fe 88 72 4 9 19 50 8 Fe92 63 2 10 12 27 9 C 10 14 1 10 0 0 10  C 5 68 7 11 10 5 11  C 90 71 1119 18 23 12  C 75 86 9 16 11 77

As obvious from Table 6, according to the sputtering targets of thepresent invention, occurrence number of dust particles, in particularthat of giant dust particles is suppressed. Based on this, occurrence oflarge concavities is made remarkably small. Further, due to remarkablylow occurrence number of the concavities, reliability as wiring is veryhigh (snapping rate is low). By employing such Al alloy films as wiringfilm, the product yield can be largely improved, and the wiring films ofuniform texture can be provided.

Embodiment 5

0.5% by weight of Cu with respect to Al is compounded with Al, theobtained compounded body being treated by use of the continuous castingmethod (atmospheric fusion) to prepare an ingot of an intendedcomposition. The atmospheric fusion is carried out while bubbling Ar.Thus obtained ingot undergoes a primary heat treatment, hot rolling,cold rolling and a secondary heat treatment, followed by machining toprepare Al alloy targets of a diameter of 320 mm and a thickness of 20mm.

At this time, by varying the respective conditions of fusion, hotrolling, cold rolling and heat treatments, a plurality of Al alloytargets are prepared. The plurality of Al alloy targets of whichdispersion degrees of Cu that is added as an element that forms anintermetallic compound and of Cr, Fe and C added as impurity element aredifferent are prepared. The dispersion degrees of these respectiveelements are measured and evaluated with the aforementioned EPMAapparatus shown in Table 1. The dispersion degree of each element isshown in Table 7.

The dispersion degree of Cu is shown by use of two area ratios in themapping of EPMA analysis. One is an area ratio (%) of a portion of whichcount number of detection sensitivity is 22 or more in a measurementarea of 20×20 μm, the other one being an area ratio (%) of a portion ofwhich count number of detection sensitivity is 22 or more in anobservation area of 200×200 μm. Each of the dispersion degrees of Cr, Feand C denotes, in the mapping of EPMA analysis, an area ratio (%) of aportion of which count number of detection sensitivity is the stipulatedvalue or more in a measurement area of 20×20 μm and an area ratio (%) ofa portion of which count number of detection sensitivity is thestipulated value or more in a measurement area of 200×200 μm.

TABLE 7 Dispersion Dispersion Degree Impurity Degree of of Cu ElementImpurity Element Sample 20 × 20 200 × 200 to be 20 × 20 200 × 200 No. μmμm evaluated μm μm 1 10 3 Cr 12 5 2 18 7 Cr 22 15 3 54 15 Cr 55 30 4 7032 Cr 80 45 5 13 2 Fe 28 3 6 25 7 Fe 34 16 7 49 21 Fe 66 20 8 81 50 Fe70 35 9 5 6 C 16 5 10 27 9 C 18 20 11 68 51 C 70 42 12 78 78 C 90 58

With each of thus obtained Al alloy targets, due to the reflowsputtering, on each of Si substrates of a diameter of 8 inches, an Alalloy film of a thickness of 300 nm is formed, respectively. Thesputtering conditions are as follows: a back pressure of 1×10⁻⁵ Pa, a DCoutput of 1.5 kW and a sputtering time period of 1 min. Of each of thusobtained Al alloy films, the dust particles are measured with the dustcounter (WM-3). The number of dust particles is obtained for each rangeof particle size. Next, the snapping rate (%) of each of theaforementioned Al alloy films is obtained similarly with embodiment 4.The results are shown in Table 8.

TABLE 8 Number of Dust Particle (dust particles of each size/wafer)Sample under 0.3 to over Snapping No. 0.3 μm 100 μm 100 μm Rate (%) 1 31 0 0 2 7 2 0 5 3 8 3 0 12 4 111 17 255 40 5 8 3 0 0 6 10 6 0 7 7 11 7 020 8 17 20 378 54 9 2 2 0 0 10 9 5 0 3 11 13 10 0 14 12 22 54 427 36

As obvious from Table 8, according to the sputtering targets of thepresent invention, though the dust particles of a size of 0.3 μm or moreare also suppressed in occurrence, in particular the giant dustparticles that are problematic in the reflow sputtering being suppressedfrom occurring. In addition, an occurrence number of concavities is alsoremarkably low. Based on this, reliability as wiring film is remarkablyhigh (lower snapping rate). By employing such Al alloy films as wiringfilm, the product yield can be largely improved, the wiring films ofuniform texture being able to be provided.

The Al wiring films obtained by sputtering each Al alloy target of theaforementioned Embodiments 4 and 5 are used as Al wiring films insemiconductor elements, LCD panels and SAW devices. As a result of this,electronic components of high reliability are obtained, respectively.

Embodiment 6

Raw material in which 6% by weight of Y is added to Al is fused by radiofrequency induction (including Ar bubbling treatment) to prepare aningot of intended composition. This ingot undergoes cold rolling andmachining to obtain an Al alloy target of a diameter of 127 mm and athickness of 5 mm. The composition of this Al alloy target is Al-6wt %Y-20 ppm Ar.

Thus obtained Al target is diffusion bonded to a backing plate made ofCu to prepare a sputtering target of the present invention. With thesputtering target, under conditions of a back pressure of 1×10⁻⁴ Pa, aDC output of 200 W and a sputtering time period of 43 min, on arevolving glass substrate of a diameter of 5 inches, an Al alloy film ofa thickness of 350 nm is formed.

Of the Al alloy film, composition, resistivity, hillock density afterheat treatment (573 K) and existence of etching residue are evaluated.The etching with a gas mixture of BCl₃+Cl₂ as etching gas is implementedto evaluate the etching residue. These results are shown in Table 9.

In addition, as comparative examples of the present invention, an Altarget (Comparative Example 1) that is prepared without adding Y and Arand an Al alloy target (Comparative Example 2) that is prepared underthe same conditions with Embodiment 6 except for without adding Ar areprepared respectively. With these targets, similarly, an Al film and Alalloy film are formed by use of sputtering, respectively. Of thesefilms, similarly with Embodiment 6, characteristics are evaluated (afterheat treatment). These results are shown together in Table 9.

TABLE 9 Result of Characteristics Target Film Evaluation of Al FilmCompo- Compo- Hillock Residue siiton sition Resistance after (% by (% byResistivity after Heat Etching weight) weight) (μΩcm) Treatment*¹ *²Embodiment 6 Al-6% Al-6% 4.1 ◯ None Y-20 ppm Y-5 Ar ppm Ar ComparativeAl Al 2.9 X None Example 1 Comparative Al-6% Y Al-6% 4.2 Δ Yes Example 2Y *¹: ◯ = Completely free of hillock Δ = hillock existing partly X =hillock existing over entire surface *²: None = free of etching residueYes = existence of etching residue

As obvious from Table 9, the Al alloy film formed by use of thesputtering target of the present invention is excellent in hillockresistance and etching property. Accordingly, by use of such Al alloyfilm as the wiring film, in addition to suppressing the hillockoccurrence, sound and fine wiring network can be formed withreproducibility.

Embodiment 7

As shown in Table 10, sputtering targets of which contents of Y and Arare varied are produced respectively similarly with Embodiment 6.Thereafter, by sputtering the targets under the conditions same withEmbodiment 6, the respective Al alloy films (Al wiring films) areformed. The characteristics of the respective Al alloy films aremeasured and evaluated similarly with Embodiment 6. These results areshown together in Table 10.

TABLE 10 Results of Characteristics Evaluation of Al Film Target FilmHillock Composition Composition Resistance Etching Sample (% by (% byResistivity after Heat Residue No. weight) weight) (μΩcm) Treatment*¹ *²1 Al-0.5% Y- Al-0.5% Y- 3.4 ◯ None 200 ppm Ar 70 ppm Ar 2 Al-0.7% Y-Al-0.71% Y- 3.8 ◯ None 300 ppm Ar 15 ppm Ar 3 Al-1.6% Y- Al-1.6% Y- 4.1◯ None 20 ppm Ar 5 ppm Ar 4 Al-2.7% Y- Al-2.65% Y- 4.6 ◯ None 2% Ar 1000ppm Ar 5 Al-4.6% Y- Al-4.6% Y- 5.1 ◯ None 900 ppm Ar 400 ppm Ar 6Al-7.0% Y- Al-6.9% Y- 6.3 ◯ None 10 ppm Ar 5 ppm Ar

Embodiment 8

Al targets in which various kinds of elements are used in the place of Yare produced (compositions are shown in Table 11) similarly withEmbodiment 6. Thereafter, under the same conditions with Embodiment 6,the sputtering targets are sputtered to form the respective Al alloyfilms (Al wiring films). The characteristics of the respective Al alloyfilms are measured and evaluated similarly with Embodiment 6. Theseresults are shown together in Table 11.

TABLE 11 Results of Characteristics Evaluation of Al Film Target FilmHillock Composition Composition Resistance Etching Sample (% by (% byResistivity after Heat Residue No. weight) weight) (μΩcm) Treatment*¹ *²1 Al-0.5% Gd- Al-0.5% Gd- 3.8 Δ None 200 ppm Ar 0.5 ppm Ar 2 Al-2.0% Gd-Al-2.0% Gd- 4.8 ◯ None 400 ppm Ar 1.2 ppm Ar 3 Al-0.5% Th- Al-0.5% Th-4.0 Δ None 250 ppm Ar 0.7 ppm Ar 4 Al-2.0% Th- Al-2.0% Th- 5.2 ◯ None600 ppm Ar 30 ppm Ar 5 Al-0.8% Re- Al-0.79% 4.0 ◯ None 500 ppm Ar Re-0.9ppm Ar 6 Al-1.5% B- Al-1.5% B- 4.1 Δ None 220 ppm Ar 1.8 ppm Ar 7Al-4.5% B- Al-4.5% B- 5.0 Δ None 200 ppm Ar 2 ppm Ar 8 Al-1.5% Sc-Al-1.46% 4.2 ◯ None 300 ppm Ar Sc-ppm Ar 9 Al-3.5% Sc- Al-3.48% 5.2 ΔNone 10 ppm Ar Sc-0.1 ppm Ar 10 Al-0.5% Nd- Al-0.49% 4.7 Δ None 20 ppmAr Nd-3 ppm Ar 11 Al-0.4% Dy- Al-0.4% Dy- 3.7 Δ None 100 ppm Ar 50 ppmAr 12 Al-2.3% Dy- Al-2.3% Dy- 4.3 ◯ None 300 ppm Ar 25 ppm Ar 13 Al-1.0%Cu- Al-1.1% Cu- 3.7 ◯ None 20 ppm Ar 7 ppm Ar 14 Al-2.0% Cu- Al-1.9% Cu-4.5 Δ None 500 ppm Ar 80 ppm Ar 15 Al-1.5% Cu- Al-1.5% Cu- 4.8 Δ None3000 ppm Ar 170 ppm Ar

Embodiment 9

6% by weight of Y with respect to Al is added to Al to prepare rawmaterial. The prepared raw material is melted by use of radio-frequencyinduction heating (while bubbling with Kr) to produce an ingot ofintended composition. The obtained ingot undergoes cold rolling andmachining to obtain an Al alloy target of a diameter of 127 mm and athickness of 5 mm. The composition of the Al alloy target is Al-6wt %Y-20 ppm Kr.

Thus obtained Al alloy target, under the conditions of back pressure:1×10⁻⁴ Pa, a DC output power: DC 200W and a sputtering period: 43 min,is sputtered on a rotating glass substrate of a diameter of 5 inches toform an Al alloy film of a thickness of 350 nm. Of the Al alloy film,the composition, resistivity, hillock density after heat treatment(573K), existence of etching residue are measured and evaluated. Theevaluation method is identical with that of Embodiment 6.

Further, as the comparative examples of the present invention, an Altarget is prepared without adding Y and Kr (comparative example 3), andan Al alloy target is prepared similarly with Embodiment 9 except fornot adding Kr (comparative example 4). By implementing sputtering witheach of these targets, an Al film and Al alloy film are formed. Thesefilms are also evaluated of the characteristics (after heat treatment)similarly with Embodiment 6. These results are shown together in Table12.

TABLE 12 Result of Evaluation of Target Film Characteristics of Al FilmCompo- Compo- Hillock siiton sition Resistance Etching (% by (% byResistivity after Heat Residue weight) weight) (μΩcm) Treatment*¹ *²Embodiment Al-6% Y- Al-6% Y- 3.9 ◯ None 9 20 ppm Kr ppm Kr ComparativeAl Al 2.9 X None Example 3 Comparative Al-6% Y Al-6% Y 4.2 Δ Yes Example4

As obvious from Table 12, the Al alloy film formed by use of thesputtering target of the present invention is excellent in hillockresistance and etching property. Accordingly, by employing such Al alloyfilm as the wiring film, in addition to suppression of occurrence ofhillock, sound and fine wiring network can be formed withreproducibility.

Embodiment 10

As shown in Table 13, Al sputtering targets in which the contents of Yand Kr are varied are produced respectively similarly with Embodiment 9.Thereafter, by sputtering the targets under the same conditions withEmbodiment 9, Al alloy films (Al wiring films) are formed respectively.The characteristics of the respective Al alloy films are measured andevaluated similarly with Embodiment 9. These results are shown togetherin Table 13.

TABLE 13 Results of Evaluation of Characteristics of Al Film Target FilmHillock Composition Composition Resistance Etching Sample (% by (% byResistivity after Heat Residue No. weight) weight) (μΩcm) Treatment*¹ *²1 1-0.5% Y- Al-0.49% 3.5 ◯ None 200 ppm Kr Y-0.7 ppm Kr 2 Al-0.7% Y-Al-0.7% 3.7 ◯ None 300 ppm Kr Y-1.1 ppm Ar 3 Al-1.6% Y- Al-1.55% 4.1 ◯None 20 ppm Kr Y-0.8 ppm Kr 4 Al-2.7% Y- Al-2.6% 4.4 ◯ None 2% Kr Y-230ppm Kr 5 Al-4.6% Y- Al-4.56% 5.0 ◯ None 900 ppm Kr Y-20 ppm Kr 6 Al-7.0%Y- Al-6.9% 6.7 ◯ None 10 ppm Kr Y-0.1 ppm Ar

Embodiment 11

Al targets in which in the place of Y various kinds of elements areemployed (compositions are shown in Table 14) are produced similarlywith Embodiment 9. Thereafter, under the same conditions with Embodiment9, the sputtering targets are sputtered to form the respective Al alloyfilms (Al wiring films). The characteristics of the respective AlEmbodiment 9. These results are shown together in Table 14.

TABLE 14 Results of Evaluation of Characteristics of Al Film Target FilmHillock Composition Composition Resistance Etching Sample (% by (% byResistivity after Heat Residue No. weight) weight) (μΩcm) Treatment*¹ *²1 Al-0.5% Gd- Al-0.5% Gd- 3.7 Δ None 200 ppm Kr 50 ppm Kr 2 Al-2.0% Gd-Al- 5.1 ◯ None 400 ppm Kr 1.92% Gd- 19 ppm Kr 3 Al-0.5% Th- Al- 4.4 ΔNone 250 ppm Kr 0.46% Th- 20 ppm Kr 4 Al-2.0% Th- Al- 5.4 ◯ None 600 ppmKr 1.91% Th- 6 ppm Kr 5 Al-0.8% Re- Al- 4.2 ◯ None 500 ppm Kr 0.75% Re-0.1 ppm Kr 6 Al-1.5% B- Al-1.49% B- 4.3 Δ None 220 ppm Kr 2.2 ppm Kr 7Al-4.5% B- Al-4.5% B- 5.0 Δ None 200 ppm Kr 18 ppm Kr 8 Al-1.5% Sc- Al-4.2 ◯ None 300 ppm Kr 1.47% Sc- 3 ppm Kr 9 Al-3.5% Sc- Al- 5.2 Δ None 10ppm Kr 3.48% Sc- 0.8 ppm Kr 10 Al-0.5% Nd- Al-0.5% Nd- 4.7 Δ None 20 ppmKr 1.2 ppm Kr 11 Al-0.4% Dy- Al- 3.9 Δ None 100 ppm Kr 0.39% Dy- 3 ppmKr 12 Al-2.3% Dy- Al- 4.3 ◯ None 300 ppm Kr 2.27% Dy- 20 ppm Kr 13Al-1.0% Cu- Al-0.9% Cu- 3.5 ◯ None 30 ppm Kr 5 ppm Ar 14 Al-1.5% Cu-Al-1.5% Cu- 4.7 Δ None 400 ppm Kr 30 ppm Kr 15 Al-2.0% Cu- Al-2.0% Cu-4.9 Δ None 650 ppm Kr 90 ppm Kr

Al wiring films formed by sputtering the respective Al alloy targets ofthe aforementioned Embodiments 6 through 11 are employed as gate linesand signal lines of LCD panels, wiring networks of semiconductorelements, and wiring of SAW devices and TPHs. As a result of this,electronic components of high reliability are obtained respectively.

INDUSTRIAL APPLICABILITY

As obvious from the aforementioned explanation, according to thesputtering targets of the present invention, giant dust particles andrelatively large concavities can be remarkably suppressed in occurrence.Accordingly, Al wiring films of the present invention formed by use ofsuch sputtering targets are extremely useful as wiring films ofsemiconductor elements, liquid crystal display devices, surface acousticwave devices or the like in which sound and fine wiring is demanded.

What is claimed is:
 1. A sputtering target, consisting essentially of:at least one kind of element that forms an intermetallic compound withAl in the range of 0.1 to 20% by weight; at least one kind of elementselected from Ar and Kr of greater than 0 and not more than 5% byweight; and the balance of Al.
 2. A sputtering target, consistingessentially of: at least one kind of first element selected from thegroup consisting of Y, La, Ce, Nd, Sm, Gd, Th, Dy, Er, Sc, Cu, Si, Pt,Ir, Ru, Pd, Ti, Zr, V, Nb, Ta, Fe, Ni, Cr, Mo, W, Mn, Tc, Re and B inthe range of 0.01 to 20% by weight; at least one kind of second elementselected from Ar and Kr of greater than 0 and not more than 5% byweight; and the balance of Al.
 3. An Al wiring film, consistingessentially of: at least one kind of element that forms an intermetalliccompound with Al in the range of 0.1 to 20% by weight; at least one kindof element selected from Ar and Kr of greater than 0 and not more than5% by weight; and the balance of Al.
 4. An electronic componentcomprising the Al wiring film as set forth in claim
 3. 5. The electroniccomponent as set forth in claim 4: wherein the electronic component is asemiconductor element, a liquid crystal display device or a surfaceacoustic wave device.